A New Transition Structure between Microstrip and Substrate Integrated Waveguide

In this paper, transition structures from microstrip to SIW (Substrate Integrated Waveguide) are proposed for an efficient transition. Transition structures reduce return loss and insertion loss by eliminating electric field discontinuity and impedance matching between microstrip and SIW. This paper proposes two transition structures using tapered lines. In the first transition structure, both the tapered lines and the SIW are designed on a single substrate. In the second transition structure, the SIW, which is designed on a separate substrate, is laminated over the substrate with the tapered lines. The single-substrate transition structure has the advantages of a simple manufacturing process and lower cost, while the laminated transition structure offers advantages in terms of design flexibility, performance optimisation and miniaturization. Both designs have reflection loss of less than 20dB and insertion loss of less than 3dB in the frequency range of 8~12GHz.